This invention relates to programming apparatus of an automatic sewing machine, more particularly to programming apparatus of sewing patterns of an automatic sewing machine utilizing a microcomputer system.
An automatic sewing machine has already been proposed in which a random access memory device, for example, a programmable read only memory device (PROM) is set in the control device of the automatic sewing machine to sew such sewing patterns as the collar, cuff, etc., of a shirt by storing data regarding movement and sequence necessary to sew such sewing patterns in the memory device (Japanese Patent Application No. 19998/1977).
The applicant has also developed a control system in which the control device disclosed in said patent application is substituted by a microcomputer and sewing pattern grooves and openings are formed through cloth clamping plates mounted on the table of the sewing machine by using a tool controlled by a programmed PROM or a read only memory device (RAM) (Japanese Patent Application No. 43803/1977). The clamping plates are used to clamp therebetween pieces of cloth to be sewed and are intermittently moved in the X and Y directions of rectangular coordinates on the table of the sewing machine, for example, by pulse motors.
According to the invention disclosed in the Japanese Patent Application No. 43803 /1977, it is possible to perform programming of the memory device and the machining of the cloth clamping plate on the same sewing machine table in addition to the ordinary sewing operations. However sewing machines constructed to perform these three functions are not only relatively expensive, and programming and machining operations on the table decreases the utilization efficiency of the sewing machine. For this reason, the customers often demand sewing machines designed to perform only the programmed sewing operations. Such demands are caused by the following problems.
A. Where the cloth clamping plates are machined on the sewing machine table, it is necessary to suitably treat the chips.
B. Where an automatic sewing machine and programming device are purchased as a set, since the time required for the sewing operation is much longer than that for the programming operation, the advantages to the purchaser who individually possesses the programming device would be greatly diminished.
C. The automatic sewing machine is designed such that the cloth clamping plates are moved 0.2 mm per one pulse of the energizing current of the clamping plate driving motor. Even when the feed speed is decreased at the time of machining a pattern groove through the cloth clamping plate, the movement per pulse is still maintained at 0.2 mm so that such intermittent movement causes breakage of the cutting tool. Where it is desired to machine a narrow groove which is necessary to improve the finishing of the sewed products it is necessary to use a thin tool, end mill for example. Accordingly, the tool would be damaged when it is fed intermittently at a rate of 0.2 mm per pulse.
D. Although it is possible to mount a tool on the head of the sewing machine for machining the cloth clamping plate and to perform the programming operation of the PROM at a place remote from the sewing machine, most of the purchasers desire to be supplied with a set of the programmed PROM and cloth clamping plates formed with sewing patterns. In other words, they wish to perform only the sewing operations.